But Microsoft is also fighting a battle against its own technology, namely Internet Explorer 6. IE6 has been declared dead many times, but it's still the browser of choice for many users and businesses despite obvious security flaws in the 9-year-old program. Microsoft itself has urged users to dump IE6.

The kill IE6 campaign is definitely making progress. North American usage has dropped from 9.33% to just 4.17% in the last year, while nearly 50% of Web surfers use either IE7 or IE8, according to StatCounter.

But getting rid of that last 4% will be difficult because many businesses have mission-critical applications that run exclusively on IE6, analysts say. Gartner analyst Ray Valdes says one financial services company he's spoken with has a custom-built application handling millions of dollars of transactions, and it only runs on IE6.

"They're scared to touch it because it works fine, and it's millions of dollars of transactions," Valdes said in an interview Tuesday.

It's an internal application, but its presence means that "employees are forced to use IE6 for all their Web activity," he says.

Other businesses are running old versions of applications that were designed for IE6 and haven't upgraded to versions compatible with newer browsers, perhaps because they don't want to pay the vendor an extra fee.

The presence of more security in versions 7 and 8 of Internet Explorer "broke compatibility with some applications," IDC analyst Al Gillen says. Even though IE7 has been on the market for four years, support for IE6 still "comes up as a regular requirement for customers, believe it or not," Gillen says.

"That's one of those cases where you might want to say to the customer 'why don't you get to the newer browser and fix the applications so you don't have the security issues,'" Gillen continued.

Compatibility modes in Internet Explorer 8 allow backward compatibility for Web applications that were not designed for the latest browser, but "there are some applications that will only work on the real IE6 and not within the compatibility mode," Valdes says.

Gillen doubts IE9 alone is enough to end the reign of IE6. After all, IE9 is not compatible with Windows XP machines.

"I don't think that IE9 specifically eliminates the need for IE6," Gillen says. "Apps written to IE6 will persist and diminish over time, no single product release such as IE9 would likely cause a sudden shift among usage demographics. Frankly, I think the move to Windows 7 is more of an influence than IE9 is."

Valdes agrees that IE9 itself won't necessarily solve "the vexing issues that are keeping organizations on IE6." But there is reason to think IE9 will help Microsoft make significant headway in weaning customers off IE6, he says.

The policies of some IT organizations state that they will support the current version of a product and two previous versions. With the release of the latest browser, IE6 will be three versions behind.

"IE9 will help because it now makes IE6 look even more ancient than it is," Valdes says.

Growing usage of Windows, which comes pre-installed with Internet Explorer 8, should also help.

But even if IE6 meets its demise in North America, usage of the aging browser could remain high worldwide. Across the globe, IE6 still accounts for 8.02% of Web browsing, down from 17.83% a year ago, according to StatCounter.

This is largely because of IE6 remaining widely used outside of North America and Europe. In Africa, IE6 still accounts for 18.07% of Web surfing. This may be partly explained by people using pirated copies of Windows XP, which are difficult to update. But even in Africa, IE6 usage has nearly dropped in half over the last year, mimicking the pattern seen in North America.

One final note on the numbers. Various organizations track Web usage statistics, with different results. For example, Net Applications research shows IE6 usage worldwide is still at 16.99%, down from 23.3% last October. But the Net Applications data agrees that IE6 usage is only around 5% in the United States and Europe.

In the Net Applications data, the global numbers are skewed by China, where nearly 50% of users are still on IE6.